1. Field of the Invention
The present invention relates to detecting the presence of a hydrate deposit or a condensate in a container, more specifically in a pipeline, by identifying certain characteristics of an acoustic signal emitted from a wall of the container in response to a spectrally broad acoustic signal being transmitted from a transducer, towards the container.
2. Description of the Related Art
Acoustic Resonance Technology (ART) is a technology where the ability of applying acoustic energy to create resonances is utilized. If a plate or pipe is insonated by an acoustic energy pulse, and the acoustic energy comprises wave components with frequencies having wavelengths corresponding to twice or integral numbers of the thickness of the plate or pipe wall, these frequencies will create standing waves across the plate or pipe wall. When the pulse comes to an end, reradiated resonant energy is detected, typically by way of a hydrophone located at a distance from the plate.
It is to be understood that, in the context of the description provided herein of the present invention, the term container is applicable to any arrangement being capable of confining a medium with respect to its surroundings, such as for example a pipeline designed for transporting oil, gas or other media that may be transported by a pipe arrangement.
The frequencies applied in the acoustic energy pulse will typically be a decade or more lower than the frequencies applied in traditional ultrasound techniques, thus offering ability to penetrate layered materials and provide characterization of various media. The energy content in the “resonant part” of the energy being returned upon insonation, and total reflected energy, is influenced by the medium on both sides of the plate or pipe wall. The medium outside submerged gas pipelines is typically seawater, while the medium contained inside the pipeline may be gas, condensate, or, occasionally, hydrate. Acoustic characteristics of these internal media will result in variations in acoustic energy being returned from the pipe when insonated by acoustic energy.